Linked Life Data

3038186

Source:http://linkedlifedata.com/resource/pubmed/id/3038186

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
1
pubmed:dateCreated
1987-9-23
pubmed:abstractText
Antimycin-insensitive succinate-cytochrome c reductase activity has been detected in pure, reconstitutively active succinate dehydrogenase. The enzyme catalyzes electron transfer from succinate to cytochrome c at a rate of 0.7 mumole succinate oxidized per min per mg protein, in the presence of 100 microM cytochrome c. This activity, which is about 2% of that of reconstitutive (the ability of succinate dehydrogenase to reconstitute with coenzyme ubiquinone-binding proteins (QPs) to form succinate-ubiquinone reductase) or succinate-phenazine methosulfate activity in the preparation, differs from antimycin-insensitive succinate-cytochrome c reductase activity detected in submitochondrial particles or isolated succinate-cytochrome c reductase. The Km for cytochrome c for the former is too high to be measured. The Km for the latter is about 4.4 microM, similar to that of antimycin-sensitive succinate-cytochrome c activity in isolated succinate-cytochrome c reductase, suggesting that antimycin-insensitive succinate-cytochrome c activity of succinate-cytochrome c reductase probably results from incomplete inhibition by antimycin. Like reconstitutive activity of succinate dehydrogenase, the antimycin-insensitive succinate-cytochrome c activity of succinate dehydrogenase is sensitive to oxygen; the half-life is about 20 min at 0 degrees C at a protein concentration of 23 mg/ml. In the presence of QPs, the antimycin-insensitive succinate-cytochrome c activity of succinate dehydrogenase disappears and at the same time a thenoyltrifluoroacetone-sensitive succinate-ubiquinone reductase activity appears. This suggests that antimycin-insensitive succinate-cytochrome c reductase activity of succinate dehydrogenase appears when succinate dehydrogenase is detached from the membrane or from QPs. Reconstitutively active succinate dehydrogenase oxidizes succinate using succinylated cytochrome c as electron acceptor, suggesting that a low potential intermediate (radical) may be involved. This suggestion is confirmed by the detection of an unknown radical by spin trapping techniques. When a spin trap, alpha-phenyl-N-tert-butylnitrone (PBN), is added to a succinate oxidizing system containing reconstitutively active succinate dehydrogenase, a PBN spin adduct is generated. Although this PBN spin adduct is identical to that generated by xanthine oxidase, indicating that a perhydroxy radical might be involved, the insensitivity of this antimycin-insensitive succinate-cytochrome c reductase activity to superoxide dismutase and oxygen questions the nature of this observed radical.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Aug
pubmed:issn
0006-3002
pubmed:author
pubmed:issnType
Print
pubmed:day
12
pubmed:volume
893
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
75-82
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1987
pubmed:articleTitle
An antimycin-insensitive succinate-cytochrome c reductase activity in pure reconstitutively active succinate dehydrogenase.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, U.S. Gov't, Non-P.H.S., Research Support, Non-U.S. Gov't